Bridges



April 1970 E. LONGBOTTOM 3,504,389

BRIDGES Filed Dec. 12, 1967 5 Sheets-Sheet 1 (mac E k t April 7, 1970 E. LONGBOTTOM 3,504,339

BRIDGES Filed Dec. 12. 1967 5 Sheets-Sheet 2 Inventor April 7, 1970 E. LONGBOTTOM 3,504,389

BRIDGES Filed Dec. 12, 1967 5 Sheets-Sheet 3 i J/M o O m S2 In fa w-7 O M i Inventor April 7, 1970 E. LONGBOTTOM 3,504,389

BRIDGES Filed Dec. 12, 1967 5 Sheets-Sheet 4 Invmtor April 7, 1970 E. LONGBOTTOM 3,504,389

BRIDGES Filed Dec. 12. 1967 5 Sheets-Sheet 5 FIG. 9. FIG.9C|.

I40 FIG. I00.

Inventor United States Patent 3,504,389 BRIDGES Eric Longbottom, Bournemouth, England, assignor to National Research Development Corporation, London, England Filed Dec. 12, 1967, Ser. No. 689,934 Claims priority, application Great Biritaiu, Dec. 16, 1966, 56,343/ 66 Int. Cl. E01d /12, 15/14 US. Cl. 1413 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates to girder structures and is particularly, but not exclusively, concerned with transportable bridges. Such bridges are frequently made in a number of sections which are assembled together to bridge, for example, a dry gap or a river. Preferably each section is light enough for it to be manhandled so that the bridge can be built without the aid of cranes and for this reason the sections are built up of a light material such as an aluminum alloy. The sections must be accurately aligned before being fastened together. The object of this invention is to provide means whereby sections of a bridge may be accurately aligned, rapidly and repeatedly, to facilitate assembly thereof.

According to the invention, girders for the construction of bridges and the like comprise a plurality of sections, each section having two end faces each'mating' with a complementary face on the adjacent section, each end face having a guide member and a tapered guide slot which engage with the tapered guide slot and the guide member on the complementary face so that the two sections are accurately positioned with respect to each other, and having means rigidly connecting each pair of adjacent sections. This invention also provides girder sections, having arrangements of guide bars and slots, for use in such girder structures and also extends to transportable bridges incorporating such girder structures. Additionally the two ends may be provided with complementary holes and tapered dowels. The guide bars may be flexibly mounted so as to deflect under load to enable the connections alone to withstand the load. A bridge constructed using girders as described, will hereinafter be referred to as a single story bridge. To provide a strengthened bridge, lower girders may be connected beneath the girders of a single story bridge, and such a bridge will be referred to as a double story bridge.

TWo forms of bridge in accordance with the invention will now be described, by way of example only, with reference to the following drawings, of which:

FIGURE 1 is a diagrammatic side elevation of a single storey bridge,

FIGURE 2 is a diagrammatic sectional end view of a single storey bridge,

FIGURE 3 is a perspective view of a girder section,

FIGURES 4 and 5 show the assembly procedure for girder sections,

3,504,389 Patented Apr. 7, 1970 FIGURE 6 is a diagrammatic side elevation of a two storey bridge,

FIGURE 7 is a diagrammatic sectional end view of a two storey bridge,

FIGURE 8 is a perspective view of a lower girder section for a two storey bridge, and

FIGURES 9, 9A, 10 and 10A show the assembly procedure for a two storey bridge.

The assembled bridge, as shown in FIGS. 1 and 2, has two load bearing girders 1, formed from interconnected sections 2, arranged longitudinally of the bridge and at the sides thereof with their ends connected by transverse end beams 3 to which are fitted ramps 4. The space between the girders 1 is filled in with light deck panels 5 and kerbs 6, shown in FIG. 2 only, are fitted to the outer upper edges of the girders 1 to help prevent vehicles from driving olf the sides of the bridges.

Each girder section 2, as shown in FIG. 3, has a hollow, generally rectangular cross section, and is sufliciently light to be carried manually. At each end of each girder section 2 is a flat compression surface 7 which extends a short distance downwards from the upper surface of the girder section and is provided at one side of the section with a projecting tapered dowel 8 and at the other side of the section with a hole 9. When the compression surface 7 of the section 2 is in contact with the compression surface 7 of another section 2 the tapered dowels 8 engage in the holes 9 and are secured therein by retaining bolts 10 which fit holes 11 in the tapered dowels 8. The ends 10a of the retaining bolts 10 are bent at right angles to their main bodies 10b and the bolts are locked by engagement of these ends 10a in slots 19 formed between the lower edge of compression surface 7 and the upper edge ofmounting brackets 20. The portion 10b of the bolt 10 is raised to fit into aperture 11 and then rotated so that portion 10a locks in slot 19 to withstand the tensile forces between the upper surfaces of two sections 2 whilst the bridge is being assembled.

Extending from each end face of each girder section 2, adjacent the lower edge thereof, are a plurality of flat tongues 12 having their planes perpendicular to the upper surface of the section 2, the tongues being so spaced apart that when two sections 2 are connected the tongues on one section are interdigitated with the tongues on the other section. When so positioned the sections are connected together by a connecting bar 13 which passes through holes 14, one in each of the tongues 12. Above one of the tongues 12, at each end of each section 2 and at one side thereof, is a plate 15 arranged with its plane parallel to the planes of the tongues 12. A horizontally disposed, open ended, tapered guide slot16 is formed in each of these plates 15, extending inwardly from the outer edges of the plate, its inner end being part circular in shape. Above the tongues 12 at each end of each section 2 and at the side thereof remote from the plate 15 is a guide bar 17, rotatably carried by two brackets 18, with its axis parallel to the common axis of the holes 14 in the tongues 12 and co-axial with the part circular shaped inner end of the tapered guide slot 16. Thus when two sections 2 are pushed into engagement the guide bars 17 slide and roll into the tapered guide slots 16 to bring the holes 14 in the tongues 12 of the two sections into register and the compression surfaces 7 into contact when the guide bars 17 are at the inner ends of the slots 16.

Each girder section 2 has deck locators 21 and deck anti-lift cleats 22 to assist in the location and retention of the deck panels. To facilitate carrying of the sections 2 carrying bars 23 may be attached to carrying bar connections 24 on the sections 2.

To assemble the bridge the girders 1 must first be built by connecting the girder sections 2 together as shown in FIGURES 4 and 5 in which, for convenience, one girder section 2 is referred to as section X and the other as section Y. A section X forming one end of a girder 1 is suitably supported and a second section Y is manually brought into alignment with it. When the two sections X and Y are pushed into contact the tapered dowels 8 engage in the holes 9 and the compression faces 7 abut; the dowels are then retained in position by sliding the retaining bolts 10 through the holes 11 therein. As the support of section Y is released, its weight pushes the guide bars 17 firmly into the inner ends of the tapered guide slots 16 thereby bringing the holes 14 in the tongues 12 into accurate alignment and enabling the connecting bar 13 (FIG. 3) to be inserted easily into the holes 14. Further girder sections are similarly connected to form the two girders 1 of the bridge.

When the two girders 1 are assembled the transverse end beams 3 and connected to their ends in a manner similar to the connnection between pairs of girder sections 2. The partly assembled bridge is now sufficiently rigid to enable it to bridge, for example, a river. In a suggested method of positioning the bridge across the river a long nose beam is fitted to one of the transverse end beams 3 and the two girders 1 are mounted on rollers. One the opposite side of the river a roller is placed to carry the nose beam whilst the bridge is being pushed across the river. When in position across the river the supporting rollers and nose beam are removed so that the transverse end beams 3 rest on the river bank. The deck panels 5, ramps 4 and kerbs 6 are then connected to the girders 1 and transverse end beams 3 to complete the building of the bridge.

In order to carry heavier loads and to bridge longer spans than the previously described bridge a two storey bridge can be constructed using the above described bridge as the upper storey, connecting bottom or lower girders beneath the girders of the upper storey and bracing the lower girders with suitably arranged bracing members.

As shown in FIGS. 6 and 7 the upper storey of the two storey bridge has girders 1 formed from girder sections 2, transverse end beams 3, ramps 4, deck panels 5 and kerbs 6 as used in the single storey bridge. In addition lower girder sections 30 are used to give the two storey structure. To allow for the increased height of the bridge an end taper panel 31 and a junction post 32 are included in the construction. Transverse bracing is provided for the girders 1 by bracing members 33.

The lower girder sections 30, shown in FIGURE 8, are equal in length to the sections 2 of the upper girder and are of triangular shape when seen in side view, having a base beam 35, a substantially upright strut 36 and an inclined or diagonal strut 37 forming an integral lower girder section. At the ends of the base beam of each lower section are spaced tongues 12a having holes 140, plates 15a having guide slots 16a, and guide bars 17a mounted in brackets 18a, similar to the items 12, 14, 15, 16, 17 and 18 on the upper girder sections 2. At the top of the upright flange 36 on each lower section are U-shaped slots 38 positioned to receive the ends of the connecting bars 13 of the upper girder 1 which are retained therein by retaining bolts 39. The lower girder sections 30 are thus connected to the upper girder sections 3 by engagement of the connecting bars 13 with the U-shaped slots 38, and are connected to one another by insertion of a connecting bar 13a into the holes 14a in the tongues 12a on the base flanges 35, the holes 14a being accurately aligned by engagement of guide bars 17a on one section with guide slots 16a of the adjacent section. The lower girder sections may be provided with carrying bar connections 24a. Also dowels 39 and jaws 41 are provided for attachment of the bracing members 33.

Assembly of the two storey bridge is very similar to assembly of the single storey bridge, and is described with reference to FIGURES 9, 9A, 10 and 10A which show connection of the two upper girder sections, again referred to, for convenience, as X and Y, and two lower girder sections referred to, for convenience, as B and C. To assist in the assembly, an assembly aid 41 (FIG. 9), consisting of a rod with forked ends 43, 44, is used. A connecting rod 13a is inserted in the holes 14a of the tongues 12a of the lower girder 8 in an assembled section X, B, of the bridge (FIG. 9). The forked end 43 of the assembly aid 42 is placed over the projecting end of the connecting bar 13a as shown in FIGURE 9A and the forked end 44 of the assembly aid 42 receives a shaped bracket, which may conveniently also constitute the carrying bar connection 24, on upper girder section Y. The upper girder section Y is then pushed toward the other section X, pivoting on the assembly aid 42, and aligned so that the tapered dowels 8 engage in the holes 9 and the guide bar 17 engages with the tapered guide slot 16. The connection between the upper girder sections X and Y is then made as previously described. The length of the assembly aid 42 is such that when the sections X and Y are brought into close contact with each other, section Y lifts slightly clear of the forked end 44, due to the taper of the guide slot 16 and the dowels 8, and the assembly aid 42 may be removed. The connecting bar 13a is withdrawn from the lower girder section B.

Lower girder section C is now manipulated so that the U-shaped slots 38 at the top of the upright flange 36 engage on the connecting bars 13 of the upper girder sections X, Y, and are locked there by the retaining bolts 39 (FIG. 10). The girder section C is then allowed to swing down, so that the guide bar 17a engages with the guide slot 16a in girder section B. Due to bar clearances, sections X, Y may droop, causing the guide bar 17a initially to engage the lower surface of guide slot 16a as shown in FIGURE 10A. The guide bar 17a is forced to the inner end of the guide slot 16a by bearing down on the end of girder section C. The holes 14a in the tongues 12a of girder sections B, C, are then aligned and the connecting bar 13a is inserted.

Similarly, the remainder of the upper and lower girder sections are assembled. Two girder sections are attached to end sections which provide ramps for the bridge. As shown in FIG. 6 a suitable end section comprises a junction post 32, which is provided with holes, tapered dowels, guide bars, tapered guide slots and tongues similar to items 8, 9, 12, 16, 17, 12a, 16a, 17a; an end taper panel 31; two upper girder sections 2; an end beam 3, and a ramp unit 4. Any suitable method of attachment may be used, but methods similar to those described for the other units in the bridge may prove to be the most convenient. Upper girder sections 2 are connected to the junction post 32 and to the end taper panel 31, the end beam 3 is then connected to the extremity of the final upper girder section and the ramp unit 4 is added.

Probably the most convenient assembly procedure will be to construct some part of the end section and to start the assembly of the girders by attaching upper girder sections 2 and lower girder sections 30 to the junction post 32. When the girders are completed the second junction post 32 is attached to their free ends. The bracing members 33 are then secured to the lower girders using the dowels 39 and jaws 41 (FIG. 8). After placing the partly assembled bridge across, e.g., a river, the assembly is completed by fitting the deck panels 5 and kerbs 6, by completing the end sections, and by adding the ramp sections 4.

The two storey bridge can be used to span considerable gaps, e.g. across rivers, with the aid of fixed piers made of, e.g., concrete, or scalfolding, or with the aid of floating piers. These piers enable a bridge to be constructed of a number of separate spans pivotally connected to one another by junction posts.

The arrangement of tapered guide slots and co-acting bars and/or tapered dowels and co-acting holes may also be used to assist the erection of cranes, especially lorry mounted cranes. Both ends of each section of a jib are provided with tapered guide slots and guide bars which align jib sections so that bolted connections can be made between the said jib sections.

I claim:

1. A girder structure comprising a plurality of girder sections each section having two end faces, each face being adapted to mate with a complementary face on an adjacent section; each end face having at its top (1) a vertical surface adapted to abut against the complementary surface of an adjacent section, said vertical surface being capable of withstanding compressive loads, and (2) a mating surface, each mating surface having a projecting dowel and a recess, said dowel and recess engaging respectively with the recess and dowel on the mating surface of said complementary face, with means for retaining said dowel against separation from said recess so retaining said vertical surface in close juxtaposition with said complementary surface; each end face also having at its bottom (1) a guide bar and a plate in which is formed a tapered guide slot for engaging respectively with the tapered guide slot and the guide bar on a complementary end face of an adjacent section to position adjacent sections accurately with respect to each other when the said vertical surfaces are in close juxtaposition, and a plurality of tongues projecting from each end face and sited away from said mating surface which tongues can be interdigitated with tongoes on the complementary end face of the adjacent section, each tongue having a hole in it located so that all the holes of said tongues are in alignment when the two sections are accurately positioned with respect to each other, and a connecting bar which is positioned to extend through the said aligned holes for rigidly connecting adjacent sections; the disposition on each end face of said mating surface, said guide bar, said plate and said plurality of tongues together with said connecting bar forming connecting means for rigidly connecting adjacent sections, being such that either end face of each section can be mated with either end face of an adjoining section.

2. A girder structure as claimed in claim 1 wherein said means for retaining said dowel against separation from said recess comprises each dowel having a diametrical hole in it and each recess having a retaining bolt for engaging with the diametrical hole in the complementary dowel.

3.- A girder structure as claimed in claim 1 and having additional girder sections underneath it to form a two storey girder structure.

4. A girder structure as claimed in claim 1 wherein said guide bar lies in a direction transverse across the end face of the section and said guide slot tapers towards the end face of the section inwards from an opening in said plate facing away from the end face, the guide slot having open sides in a direct-ion transverse across the end face whereby the guide bar can enter and be located in the inner end of the slot.

5. A bridge span comprising two girder structures as claimed in claim 1 laterally spaced and having deck panels extending from one girder to the other.

6. A bridge span comprising two girder structures as claimed in claim 3 laterally spaced and having deck panels extending from one girder to the other.

7. A girder section, for use in the lower storey of a two storey girder structure as claimed in claim 3, having a plurality of upper and lower girder sections, said girder section having a triangular frame comprising a base beam, a substantially upright strut and an inclined strut, the base beam having at each end a guide bar and a plate in which is formed a tapered guide slot which can engage respectively with the tapered guide slot and the guide bar on the complementary end of the base beam of an adjacent section so that the two sections can be accurately positioned with respect to each other, and means whereby each face can be rigidly connected to the complementary face of an adjacent section.

8. A girder section as claimed in claim 7 wherein said substantially upright strut has at its top end upright slots for engaging a connecting bar in the upper girder structure, said substantially upright strut also having at its top end slidable pins for retaining said connecting bar in said upright slots.

9. A girder section for use in a structure having a plurality of girder sections, said girder section having two end faces, each end face having at its top (1) a vertical surface adapted to abut against the complementary surface of an adjacent section, said vertical surface being capable of withstanding compressive loads, and (2) a mating surface, each mating surface having a projecting dowel and a recess with said dowel and recess being engageable respectively with the recess and dowel on the mating surface of said complementary face, with means for retaining said dowel against separation from said recess so retaining said vertical surface in close juxtaposition with said complementary surface; each end face also having at its bottom (1) a guide bar and a plate in which is formed a tapered guide slot for engaging respectively with the tapered guide slot and the guide bar on a complementary end face to position adjacent sections accurately with respect to each other when the said vertical surface are in close juxtaposition, and a plurality of tongues projecting from each end face and sited away from said mating surface which tongues can be interdigitated with tongues on the complementary face of an adjacent section, each tongue having a hole in it located so that the holes on both sets of tongues are brought into line when the two sections are accurately positioned with respect to each other for receiving a connecting bar for rigidly connecting the face to the complementary face of an adjacent section; the disposition of said mating surface, said guide bar, said plate and said plurality of tongues forming connecting means, being such that either end face of said section may be mated with either end face of an adjoining section.

10. A girder section as claimed in claim 9 wherein said means for retaining said dowel against separation from said recess comprises each dowel having a diametrical hole in it and each recess having a retaining bolt which can engage the diametrical hole of the dowel on said adjacent section.

11. A girder section as claimed in claim 9 wherein said guide bar lies in a direction transverse across the end face of the section and said guide slot tapers towards the end face of the section inwards from an opening facing away from the end face, and the guide slot has open sides in a direction transverse across the end face whereby the guide bar can enter and be located in the inner end of the slot.

References Cited UNITED STATES PATENTS 2,339,098 1/1944 Nagin l413 2,376,023 5/ 1945 Bailey 14--13 2,669,960 2/1954 Laycock 14-27 XR 2,681,190 6/1954 Thomson 14-27 XR 3,036,539 5/1962 Storey l4-27 XR 3,386,117 6/1968 Sterner 14-27 3,394,419 7/1968 Sedlacek l413 FOREIGN PATENTS 1,060,280 6/ 1959 Germany. 1,104,848 4/ 1961 Germany.

JACOB L. NACKENOFF, Primary Examiner US. Cl. X.R. 14-27 

